ya glad we didn't set you up with something thinking it was a small truck lol.
happen to know your alternators size? $1500 is a nice budget but i don't want to link stuff thats going to rape your stock electrical system.
we're looking at 4X 6.5inch speakers and 2X 4x6inch speakers and 2 subs most likely. i wouldn't recommend making your own box unless you are wanting to do a specifically tuned ported box which can get complicated.
big 3 upgrade walkthrough
http://www.youtube.com/watch?v=p82xRzCr-lc